Computed tomography (CT) plays an important role in the diagnosis and management of disease and injury. The long-term risks of CT are unknown, but children and young adults represent a susceptible group for radiation-related cancer. The proposed study provides a unique opportunity to assess the safety of CT scans in children and to gain more information on a potentially important risk factor for cancer in children and young adults.

We are collecting detailed electronic information on over 200,000 patients (<22 years at the time of their first scan) scanned using CT prior to 2002. This information, including radiological, clinical and demographic details, will be downloaded from the information systems in radiology departments across the UK and linked with the National Health Service Central Registry so that cancer and mortality information can be obtained.

A cohort analysis of all 200,000+ patients will assess cancer risk in relation to a radiation dose estimated by an expert dosimetrist. A nested case-control study will involve the abstraction of more detailed information, including scan parameters, to allow estimation of doses.

The study also spearheads a planned international study of the long-term risks associated with CT.